Electric regulator of the carbon pile type



April 10, 1945. 1.. k. NIXON 2,373,591

ELECTRIC REGULATOR OF THE CARBON FILE TYPE Filed May 16, 1942 2 Sheets-Sheet l A: Al/fl 5 J: g 5

F ii 1 l fl 5 i 0 L f April 10, W45, Y L. R. NIXON 2,373,591

ELECTRIC REGULATOR OF THE GARBON PILE TYPE Filed May 16, 1942 2 Sheets-Sheet 2 Patented Apr. 10, 1945 ELECTRIC REGULATOR OF THE CARBON PILE TYPE Leslie Reginald Nixon, New Eltham, London S.l:..8,

England, assignor to J. Stone & Company Limited, Deptford, England, a company of Great Britain Application May 16, 1942, Serial No. 443,315 In Great Britain August 29, 1941 .6 Claims.

This invention comprises. improvements in and connected with electric regulators of the carbon p le type.

Spring systems for such regulators have been proposed, having a spring rate which increases progressively as the clapper armature or core is attracted by the magnet. These spring systems have comprised two. springs, in series, such springs co-operating during fiexure mutually t shorten their eiiective lengths and thereby to increase their combined stiffness. For example, a spring system has comprised two bowed blade springs with their concave surfaces towards one another, one blade resting against an abutment and the other blade being engaged by means such as a rod extending from the magnet armature. Under initial loading for the maximum compression of the pile, the ends parts of the blades are flattened somewhat against one another. When the magnet is energized and attracts its armature, the latter compresses the spring arrangement to the relief of the pile, whereby the end parts of the spring blades flatten against one another to an increasing extent, leaving only the middle portions oppositely bowed. The effect of this is that during magnetic attraction of the armature and the consequent shortening of the air gap, the spring arrangement acquires a progressive stiffness.

A spring system such as that described in the preceding paragraph and which may be said to comprise a double-V spring arrangement, can be shown to have the following law:

A spring system of this order may give characteristics having the disadvantage that they result in a voltage lacking a desirably high degree of accuracy and even in instability of the regulator.- The object of the present improvements is to remove this disadvantage and to provide a spring system adapted for giving very accurate regulation and complete stability.

According to the. present invention, a spring arrangement of variable rate is combined with a secondary spring of substantially constant low rate, which is arranged to operate in parallel with the spring arrangement aforesaid, and by this combination, adjustment of the slope of a characteristic can be very conveniently controlled by merely varying the initial loading forces to which the component springs are set by abutment screws.

According to one form of the invention a spring system is advantageously used which comprises spring arrangement aforesaid.

In order to enable the invention to be readily understood reference is made to the accompanying drawings wherein:

Figure 1 is a diagram showing the inherent characteristic of a double-V spring arrangement and magnet and pile characteristics.

Figure 2 is a diagram showing voltage regulating characteristics.

Figure 3 is a diagram showing the spring characteristic seen in Figure 1 and modified characteristics.

Figure 4 is a diagrammatic sectional elevation of a combination spring system in accordance with the present improvements.

Figure 5 is a diagram showing different voltage regulating characteristics, and

Figure 6 is a diagram similar to Figure 3 but showing other characteristics obtained by means of adjustable spring abutments.

Figure 7 is a sectional elevation illustrating a spring system similar to that illustrated in Figure 4- as applied to an electric regulator, the section being taken on the line VIIVII of Figure 9.

Figure 8 is a view similar to Figure 7 but with the section taken on the line VIII-VIII of Figure 9.

Figure 9 is a top plan view of Figure 7.

Figure 10 is a perspective view illustrating the bowed spring plates removed from the regulator seen in Figures '7 to 9.

Figure 11 is a fragmentary sectional elevation illustrating a modification of the spring system seen in Figure 8.

Figure 12 is a side elevation of another construction of carbon pile regulator embodying a spring system in accordance with the present improvements.

Figure 13 is a plan of Figure 12, and

Figure 14 is a perspective view illustrating a modification of the regulator seen in Figures 12 and 13. A,

Figure 15 is an inverted sectional plan and Figure 16 is an elevation illustrating a spring system comprising the combination of bowed spring plates and a blade spring, the section for Figure being taken on the line XV-XV of Figure 16.

Referring to Figure 1, wherein force is plotted vertically, asindicated by F, and gap length is plotted horizontally, as indicated by GL, the curve marked 3 is the spring characteristic and is very similar in form to the curve marked M which is the magnet characteristic with constant excitation. The curve marked P is the carbon pile characteristic. The dotted curve marked M +P is the combined characteristic of magnet and pile. Now, the ideal spring characteristic is one which corresponds with the dotted curve M +P and not with the curve S, for the spring force should at all points equal the sum of the magnet and pile forces.

In Figure 2 voltage is plotted vertically, as indicated by V, and pile resistance is plotted horizontally, as indicated by PR. The full-line curve is the characteristic of a simple spring system having a characteristic such as that marked S in Figure l. The dotted-line curve, however, is the regulating characteristic which would be obtained with an ideal spring system having the characteristic shown by the dotted curve in Figure 1. With the ideal spring system it will be seen that the lower limitof the effective rang-e of carbon pile resistance has been reduced from R2 to R1. I

In Figure 3, the simple spring curve S of Figure 1 has been reproduced for convenience. Figure 3 also shows a characteristic S1 which may be obtained with a similar simple spring system but with different design proportions such as those giving a smaller initial slope to the sides of the Vs. In addition, Figure 3 shows the characteristic C1 of a low rate spring. The combina--' tion of the two characteristics C1 and S1 results in a characteristic C1+S1 which is a close approximation-to the ideal characteristic M P in Figure l. I

Figure 4 illustrates one combination of springs in accordance With the present improvements. This combination comprises a so-called double- V spring W and a low rate coil spring C and these springs press against a bridge piece 13 which is in contact with rods R. attached to an armature M. The outer end of the coil spring C rests against an abutment screw A which is adjustable in the framing of the regulator and the'spring C passes through a hole in the double-V spring so as tobe able to press freely with its inner end against the bridge piece B The double-v spring consists of two oppositely bowed blades or plates which may be connected together at one end by a rivet, as shown, the inner blade bearing against the bridge piece 13 and the outer blade resting against abutment screws one on either side of the screw A and therefore not seen in Figure l. The several abutment screws serve forthe initial loading of the springs for maximum compression of the pile (not shown) to which pressure is transmitted by way of the rods R, armature M and rod N.

A combination of springs such as hereinbefore described presents the advantage of a very convenient and useful adjustment of the slope of the regulating characteristic. v

With a simple double-V spring, and if this has been designed to give a slightly difierent characteristic'from that required by the magnet, the voltage regulating characteristic may be either drooping or rising as compared with the ideal. For example, in Figure 5, V1 is the ideal characteristic, whereas V2 rises in consequence of too steep a spring rate being used and V3 falls in consequence of the spring rate being too low. The characteristics V2 and V3 have the disadvantage that they result in less accurate voltage regulation and the drooping characteristic V3 has the further disadvantage that it is likely to cause instability of the regulator. The steepness of the characteristic of a double-v spring can be controlled by adjustment of the angle contained by the Vs or by other dimen' sional adjustments, none of which is a convenlent method to apply on test. With a combination of springs as provided by the present improvements adjustment of the slope of the characteristic can be very conveniently controlled by varying the initial loading forces to which the springs are adjusted by means of their abutment screws.

In Figure 6, the characteristics S1, C1 and C1+S1 of Figure 3 are reproduced. If the abutment screw or screws of the double-V spring is or are tightened the dotted characteristics S2 can be obtained. This, combined with a lower force from the coil spring, as represented by the dotted curve C2 gives an addition shown by the dotted curve C2+Sz. By this means it will be seen that the general slope of the combined spring characteristic has been increased.

Figures '7 to 10 illustrate a construction very similar to that seen in Figure 4 but in greater detail. In this construction the armature M is seen to be connected by a pair of rods R with a bridge piece 13. The bridge piece is connected with a thin flexible plate or diaphragm D supported on the framing E and serving for the guidance of the rods R and armature M. The abutment screw A for varying the compression of the coil spring C is in this example cupped to receive one end of such spring. The other end of the spring 0 passes through holes H (seen clearly in Figure 10) formed in the spring plates W and presses against the bridge piece B. The screw A screws through a hole in the back plate E of the framing E and on each side thereof are screws J which also screw through the back plate E and engage one of the plates of the spring W for varying the compression of such spring and its loading on the bridge piece B. The spring plates W may be connected together at one end by a rivet K and may be formed with small holes H Figure 10, for engagement with pips or projections 0n the ends of the screws J, such engagement being effective for retaining the spring plates W in their proper position. The armature M has connected to its undersidera rod N for transmitting pressure to a carbon pile (not shown). The rod N and armature M are connected also with a thin flexible plate or diaphragm D which is supported on the framing E and co-operates with the diaphragm Din the guidance of the rods R and the maintenance of the armature M parallel with the poles O of the electro-magnet. Q indicates the coil of the electro-magnet and T indicates a laminated magnet structure providing the poles 0 More said. It will be apparent that when the coil Q is energized the armature M is attracted towards the poles 0, thereby relieving pressure of the rod N upon the pile and further compressing portions bowed towards one another.

spring action of the plates W acquires considerably increased stiffness and resistance under such further compression, whereas the resistance of the coil spring C increases almost. im perceptibly under such further compression, these conditions being in accordance with what has already been explained by the aid of the diaphragm. By adjusting the screw A or the screws J, or both A and J, the initial loading of the springs can be altered to suit the various requirements hereinbefore explained.

According to the modification illustrated in Figure 11, the initial compression of the spring plates W is adjusted by a single adjustment screw J which is disposed in the middle. In this case, two coil springs C are used disposed one at each side of the screw J and each of the springs C is engaged with an adjustable screw A by means of which its initial compression can be altered.

In the further modification illustrated in Fig- .ures 12 and 13, T again indicates a laminated magnet structure providin poles O and adapted for being energized by a coil Q. In this case, however, a pivoted armature M is employed, the pivot I being disposed between the armature M and an extension M thereof. The carbon pile 2 rests upon a frame member of the regulator and is pressed upon by the extension M through the medium of a ring 3. The latter is disposed in a hole l (Figure 13) formed in the extension M and is pivotally supported on a fixedly mounted pin 5. A blade spring diametrically fixed on the ring friotionally engages areduced middle portion of the pin 5 so that pivotal movement of the ring 3 about the pin 5 is stiff. Thus, in spite of tilting movements of the extension M the ring 3 always initially applies pressure squarely and evenly to the pile 2. A spring W, consisting of two oppositely bowed spring plates similar to those hereinbefore described, rests with its lower blade upon a block I on the framing, this block and the spring plates being perforated for the passage of rods 8 which are pivotally connected with the armature at 9. The outer ends of the rods 8 are screw threaded to receive nuts Hi, the adjustment of these nuts iii being effective for altering the initial compression of the spring W. A rod H is bent to a U form and the limbs of the U are then bent to provide horizontal and vertical portions. The ends of the horizontal portions are fixed in the armature M the loop at the bottom of the vertical portions which are outside of the framing, serving as an anchorage for the lower end of a coil spring E2. The upper end of the spring I2 is hooked to the lower end of a screw [3 which extends upwards through a hole in a lug on the framing and through the nut M having knife edge projections 55 for hearing in notches in the said lug, as will be apparent from Figure 12. This nut l4 screwing on the screw 13 serves for adjusting the initial tension of the spring I2. The spring W acting against the nuts it exerts an upward pull on the rod 8 and consequently upon the armature M This tends to depress the armature extension M and to compress the pile 2 through the medium of the ring 3. The action of the spring W is assisted by the upward pull or the coil spring E2 on the bent rod ll fixed to the armature M The combined action of the springs W and i2 is opposed by the armature M when the coil Q is energized, increasing energization of the magnet having the effect of increasing the compression of the spring W and relieving the compression exerted on the pile 2 by the springs. With increasing compressionoi the spring .W, theend portions of the plates thereof increasingly flatten against one another and thereby increase the stiffness of the spring W as and for the purpose already explained, whereas the action due to the coil spring i2 is only slightly changed during armature movements.

Figure 14 illustrates a construction somewhat similar to that illustrated in Figures 12 and 13. In Figure-l4, however, the double plate spring W is engaged by the top bar of a metal loop or frame i I having its bottom bar engaged with the armature M The latter is not supported by a pivot pin but is attached by a clamping plate E8 to a flexible strip is. pivotal movements of the armature M being permitted by the flexing of the strip id. The extension M of the armature in this case is forked for enabling the presser ring 3 of Figures-l2 and 13 to be mounted between the prongs of the fork. The spring W rests with its lower bowed plate upon a frame plate 26 which can be adjusted up or down by means of nuts 2! in order to vary the initial compression of the spring W. it indicates a nut for adjusting a screw 13 which has attached to it a coil springin the same manner as the screw i3 has attached to it the coil spring 12 in Figure 12. In this con struction, attraction of the armature M towards the magnet poles O is opposed by the spring W acting against the top bar of the frame H attached to the armature M In other respects, the operation is the same as that described with reference to Figures 12 and 13.

According to the further modification illustrated in Figures 15 and 16, the auxiliary spring takes the form of a blade spring 22 instead of a coil spring such as that marked C or !2 in the preceding figures. In this modification, the ends of the armature rods R which pass through the diaphragm D are reduced and screw threaded to receive nuts 23 and 24. The nuts .23 securely connect the rods R with the diaphragm D and the nuts 24 securely connect the wide end or base of the blade spring 22 with the rods R, the blade spring 22 as will be apparent from Figure 15, being of a somewhat triangular shape as seen in plan. The apex or narrow end of the blade spring 22 is engaged by a screw 25 which can be adjusted in the back plate E of the frame for increasing or decreasing the fiexure of the blade spring 22. The lower bowed plate of the spring device W is engaged by the extremities of the armature rods R and the upper plate presses against an adjustable screw or screws J. The loading due to the spring W can be varied by adjusting the screw or screws J and the loading due to the spring 22 can be varied by adjusting the screw 25. When the armature is attracted the spring W is compressed and increases in stifiness as already explained. The blade spring 22, however, merely flexes and the action due thereto changes only slightly during armature movements.

I claim:

1, In an electric regulator of the carbon pile type, the combination of a resistance pile, presser means engaged with one end of said pile, a rigid abutment, a variable rate spring operative between said abutment and said presser means for compressing said pile, a substantially constant low rate spring operative between said abutment and said presser means and in parallel with said variable rate spring, and an electro-magnet operative upon said presser means in opposition to said springs.

2. In an electric regulator of the carbon pile type, the combination of a resistance pile, presser means engaged with one end of said pile, a rigid abutment, a main spring operative between said abutment and said presser means for compressing said pile, said main spring being of the kind which progressively increases its stiiiness under compression, a substantially invariable low rate spring operative between said abutment and said presser means and in parallel with said main spring, and an electro-magnet operative upon said presser means in opposition to said springs.

3. In an electric regulator of the carbon pile type, the combination of a resistance pile, presser means engaged with one end of said pile, a rigid abutment, a main spring operative between said abutment and said presser mean for compressing said pile, said main spring comprising two, oppositely bowed plates adapted to flatten against one another under compression and thereby to progressively increase the stiifness of such main spring, a substantially constant low rate spring operative between said abutment and said presser means and in parallel with said main spring, and an electro-magnet operative upon said presser means in opposition to said springs.

' 4. In an electric regulator of the carbon pile type, the combination of a resistance pile, presser means engaged with one end of said pile, a rigid abutment, a variable rate spring operative between said abutment and said presser means for compressing said pile, a spring adjustment operable for varying the compression loading on said pile due to said variable rate spring, a substantially constant low rate spring operative between said abutment and said presser mean and in parallel with said variable rate spring, and an electro-magnet operative upon said presser means in opposition to said springs.

5. In an electric regulator of the carbon pile type, the combination of a, resistance pile, presser means engaged with one end of said pile, a rigid abutment, a variable rate spring operative between said abutment and said presser means for compressing said pile, a spring adjustment operable for varying the compression loading on said pile due to said variable rate spring, a substantially constant low rate spring operative between said abutment and said presser means and in parallel with said variable rate spring, a second spring adjustment operable for varying the compression loading on said pile due to said constant low rate spring, and an electro-magnet operative upon said presser means in opposition to said springs.

6. In an electric regulator of the carbon pile type, the combination of a resistance pile, presser means engaged with one end of said pile, a rigid abutment, a leaf spring operative between said abutment and said presser means for compressing said pile, said leaf spring being adapted for shortening its effective length and thereby attaining increased stifiness under increased compression, a substantially low rate coil spring operative between said abutment and said pressermeans and in parallel with said leaf spring, and an electromagnet operative upon said presser means in opposition to said springs.

LESLIE REGINALD NIXON. 

